Field and greenhouse experiments were conducted to determine the effec
t of selected insecticides on cotton when applied in combination with
pyrithiobac. In the field, acephate, azinphos-methyl, bifenthrin, chlo
rpyrifos, dicrotophos, esfenvalerate, malathion, methomyl, or oxamyl w
as applied foliarly with the sodium salt of pyrithiobac at 70 g ae/ha.
Pyrithiobac plus malathion resulted in greatest injury when compared
with other treatments. There were no differences observed in fruiting
characteristics of cotton. Cotton yield was lower with oxamyl, methomy
l, and chlorpyrifos when applied in combination with pyrithiobac in on
e of three experiments. In greenhouse experiments, injury due to pyrit
hiobac was greater in a cool (21 C day, 13 C night) temperature than i
n a warm temperature (30 C day, 21 C night), but differences were less
than 15%. Pyrithiobac plus malathion in the cool environment injured
cotton more severely 7 DAT than either pesticide alone. Adding insecti
cides to pyrithiobac did not influence injury in the warm environment.